by Mary Cooch.
Well this is of no help and I know it's annoying when people say this - but - I too have a site (personal, not an HQ one) on 3.1 with Centos 6.7 and MySql and it does work with online text (and others ) I just double checked with the online text assignment. Do you see the student submission also in the feedback box if you have that enabled and are you able to comment inline in that box? I'm not a technical person - I got someone else to set up the site and someone else to add Ghostscript and unoconv - but if you can think of something I could check so we can do "compare and contrast" with our two sites, I'd be happy to do so. Mine's online on a VPS.